Pythian Group

At the 2008 MySQL Conference and Expo, The Pythian Group gave away EXPLAIN cheatsheets. They were very nice, printed in full color and laminated to ensure you can spill your coffee* on it and it will survive.

For those not at the conference, or those that want to make more, the file is downloadable as a 136Kb PDF at explain-diagram

* or tea, for those of us in the civilized world.

Have you ever heard the one about throwing hardware at a software problem?

In one of my previous blog posts, I mentioned something along the lines of—well I’ll just cut and paste . . .

In my experience, the solution to most problems (the ones the caller refers to as “it’s running slow”) are not rooted in hardware, because hardware problems generally cause things to not run at all. It always baffles me when developers and architects prescribe hardware upgrades to make things run faster, because about 80% of the performance-related problems and subsequent solutions I’ve dealt with were resolved by tuning the application.

Well yes, I know you can buy new hardware, and it’s easier. But when it comes to hardware, how many of you have a ten-node RAC cluster running Enterprise Edition with 8GB of RAM on each node, running off a massive SAN?

I’ve been on so many systems that have been running for years–poorly–the way they were, and in a week we can take them apart and have them running without a hitch. We’ve even managed to fix problems that turned out to be the business case to go from RAC back down to a single instance. How much did those customers save on licensing costs?

Back to the example at hand. I have this nifty RAC system that supports some very public and very mission-critical apps, and one day (it was Sunday night) it starts choking. We’re getting enqueues. Slowly they start climbing. Ten nodes came to a crashing halt. I have now seen a ten-node RAC cluster come to crashing halt and completely lock up.

Why, you ask? Read the rest of this entry . . .

First of all “the before” time is over — I’m done with my presentation. It’s been the first slot of the day — 8:30 and Cary Milsap was presenting in another hall so what chances do I have to get people in? It turned out that some people actually did show up and quite a few considering the circumstances.

I have mixed feeling on the results. The presentation started very well and I managed to wake people up at the very beginning — thanks to the “equipment” I had at hands (thanks Marco and Riyaj!). You can spot one of them on the photo (thanks for the photo Marco):

Read the rest of this entry . . .